Measurements of the electrical properties of coal measure rocks

Subsurface imaging technologies are part of the electromagnetic (EM) geophysical methods. EM technologies such as radio imaging method (RIM), ground penetrating radar (GPR), and drill string radar (DSR) have great application potentials in the mining industry.;However, the success for applying the EM methods to subsurface observations is largely dependant on the correct evaluation of the electrical properties (e.g., wave attenuation rate and dielectric constant) of the rocks in the domain of interest. Study of the electrical properties of rocks was performed in order to gain better understanding about their variations across the country. The study was done specifically for rocks associated with coal seams. The findings are to be used for improvement of the exploration capabilities of the electromagnetic (EM) technologies in the mining industry.;A large amount of data was collected and available for use to the potential users via the database that was developed

Two-dimensional gravity modeling of the Rattlesnake Springs watershed, Carlsbad Caverns National Park, New Mexico

A series of non-invasive geophysical investigations at the Rattlesnake Springs part of Carlsbad Caverns National Park, New Mexico, were performed in an effort to better delineate the watershed of the springs. The goal of this project is to determine possible locations of fractures and faults that may control the distribution of groundwater that feeds Rattlesnake Springs. Once the water flow paths are identified, the park will be able to better protect Rattlesnake Springs from environmental hazards, such as oil and gas drilling, as well as from upstream water development. As part of this effort I conducted a precision gravity survey of the area surrounding the springs. The survey used 200- to 300-m grid spacing with station positions and elevations determined using differential Global Positioning System (GPS) receiver. The survey was designed to map the depth to gypsum bedrock in the study area, and to pinpoint the locations of faults and fractures that could control groundwater movement toward the springs. I generated gravity maps from the gravity data, and also constructed two-dimensional (2D) gravity models in order to gain more complete understanding of the subsurface including the locations of the probable geological structures that are controlling the water flow towards the springs. From the models, the approximate maximum depth to the gypsum bedrock in the small basins was found to be anywhere between 800 to more than 2000 meters in the study area. Verification of the locations and orientation of these hypothetical geological structures (fractures) was done as a part of my effort. The study is important to the National Park Service personnel from an environmental point of view due to the fact that it will assist them to protect the Rattlesnake Springs area from potential groundwater contamination due to oil and gas drilling performed at nearby sites. Once the Park Service knows the orientation of the possible fracture zones, they will be able to perform more accurate hydrologic modeling of the area in order to better define the ground water flow paths